The virus disease of ferns was described for the first time by HINO in 1933 who mentioned 10 species as the hosts of the disease and pointed out the fact that the ferns might be recognized to be the lowe t group of plants susceptible to the disease ever recorded. Since then there have been no records of the virus affecting ferns. Eight new hosts are mentioned in this paper and the X-body found in the epidermal cells is fully herein described. A green aphid is suggested to transmitt the disease. The virus is perpetuated by the rhizome.
Dew and rain water on mosaic tomato leaves contain free virus of the disease. Nicotiana sp. was used as test plant because the virus, which appears to be a strain of the ordinary tobacco mosaic virus, produces necrotic local lesions on the leaves. Samples of dew or rain water were gathered carefully from the surface of the mosaic tomato leaves and were filtered through “Seitz-Entkeimungs-Schichten”. The. filterates were then rubbed over the leaves of Nicotiana sp. which were dreviously dusted with finely ground carborundum abrasive. Within a few days after the inoculation, numerous local lesions peculiar to the virus infection appeared on the rubbed leaves. Although the mechanism of the appearance of the virus in such water droplets is still obscure, it is highly probable, however, that the virus had not been brought to the surface of the leaves by such external agent as dust from the soil, because the virus was found to be in extremely low concentrations, in both the soil and the rain water of non-diseased plants.